Teachers could reduce their workload by outsourcing the marking of pupils' school work to staff overseas, suggests a leading education researcher.

Rebecca Allen, director of Education Datalab, says research has found "incredibly reliable" marking available overseas costing £2 to £3 per hour.

Dr Allen says there needed to be more radical approaches to cutting workload.

But heads' leader Brian Lightman said he would have "serious concerns" about regularly outsourcing marking.

Mr Lightman, leader of the ASCL head teachers' union, said: "Marking of pupils' work is an integral part of the professional duties of a teacher."

Dr Allen, speaking at an Education Media Centre event, suggested that even though all political parties backed the idea of cutting workload for teachers, there were few practical measures to achieve this and "radically different ways" should be considered.

She said schools should consider re-thinking some of the most time-consuming activities, such as marking pupils' work.

Cutting workload

"We've got to look elsewhere. We can't just say things like 'paperwork'. I think we need to be realistic and think in radical ways about things like marking," said Dr Allen, who is also reader in the economics of education at the UCL Institute of Education.

Marking remained popular with parents and was seen as providing evidence for inspections and so teachers were likely to remain under pressure to carry on with large amounts of marking.

As such she suggested that there needed to be more imaginative ways of tackling the workload.

One approach could be to "outsource marking".

She said research projects had found accurate marking could be carried out overseas, in countries such as India, for about £3 per hour or less.

Another approach likely to be explored was using computer technology, she said.

There have already been some experiments with outsourcing the marking of vocational qualifications, with candidates' answers being scanned into a computer system in the UK to be checked by staff in India.

But heads' leader Mr Lightman said: "Whilst we would agree that technology can, in appropriate cases be used to process some assessments, I would have serious concerns about outsourcing routine marking.

"Teachers need to see pupils' work themselves so that they can fully understand the degree to which their pupils have understood what has been taught.

"Schools must be resourced adequately to provide them with the time to do this.

"The unnecessary workload surrounding marking has been caused by a high stakes accountability system which places teachers under intense pressure to provide 'evidence' to justify their assessment decisions."

Kevin Courtney, deputy general secretary of the National Union of Teachers, said: "Teachers don't just look at the rightness or wrongness of the student's answer - they want to understand and support the student's learning process. Outsourcing doesn't help at all with assessment for learning."

Teachers' unions have frequently complained that excessive workload is one of the major problems for the teaching profession.

It has been blamed as a barrier for recruiting teachers and a reason for those leaving the profession.